Heart preservation chamber

ABSTRACT

A heart preservation chamber is disclosed which comprises a housing, an inclined trough support surface, and inlet and outlet fluid connections for the major heart blood vessels.

RELATED APPLICATION

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/403,556, filed Aug. 14, 2002. The entire teachings ofthe above application is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] This application relates to the field of heart preservation,resuscitation, evaluation and maintenance.

[0003] Organ preservation devices, such as the POPS™ system designed byTransMedics, Inc., often require a specially designed chamber to housethe organ. Examples of such organ preservation devices are described inU.S. Pat. Nos. 6,046,046 and 6,100,082, the entire teachings of whichare incorporated herein by reference.

[0004] Recent advances in the field of organ preservation have led to adesire to have the organ kept in a functioning and viable state duringthe preservation period. To do so, the organ must be maintained in a waythat allows it to so function. Previous containers for the heart havebeen constructed to have the heart suspended from the cannulas whichdeliver blood to and take blood away from the heart's arterial andvenous vessels, respectively. However, such suspension of the heart byits vessels can cause problems of aorta tearing and heart ischemia overlong periods of time. Alternatively, previous containers and methodshave allowed the heart to lay on a flat surface. These devices have ledto a lack of tension on the aortic root which interferes with thecompetency of the heart valve leaflets. Again, ischemic tissue results.

SUMMARY OF THE INVENTION

[0005] The heart preservation chamber of the present invention allows aheart to be housed in a container which permits it to continue beatingand pumping blood through all of its chambers and vessels. This isaccomplished by providing cannulas that are inserted into the aorta,pulmonary artery, and pulmonary vein(s).

[0006] The heart preservation chamber of the present invention alsosolves the problems of prior organ chambers which suspend the heart byits vessels or allow it to lay on a flat surface. The present chamberhas an inclined surface which provides the optimal balance betweensupporting the heart and maintaining aortic valve competence. The heartrests on an inclined trough and is cannulated through the aorta,pulmonary artery, and pulmonary vein(s). The cannulation of the aortahelps maintain aortic valve competency, while the incline support of theorgan allows a significant portion of the organ's weight to be supportedby the support surface and not by the cannulated vessels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

[0008]FIG. 1 is a diagram of the heart preservation chamber in an openposition.

[0009]FIG. 2 is a diagram of the heart preservation chamber in a closedposition.

DETAILED DESCRIPTION OF THE INVENTION

[0010] A description of preferred embodiments of the invention follows.

[0011] The heart preservation chamber comprises a housing that typicallyis at least partially transparent, has an inclined trough, preferablyv-shaped, for supporting the heart, and includes a connector for theaorta attached to the upper wall of the chamber, at least one otherinlet means and at least one other outlet means through the walls of thechamber for connecting fluid from or to a preservation fluid circuit tothe heart. Sterilized cable straps tighten around the heart bloodvessels, to the connectors, creating a leakproof seal with the chamber.In a preferred embodiment, the heart preservation chamber provides asterile sealed, warm, moist environment for preserving and maintaining aviable, functioning heart.

[0012] The housing typically is at least partially transparent to allowthe heart to be viewed during the preservation period. The supportsurface for the heart is an inclined trough, which is preferablyv-shaped, to provide lateral support for the heart duringtransportation. The cannulation of the heart's vessels serves to deliverto and take fluid away from the heart, provide tension on the aorta tomaintain aortic valve competence, as well as to provide some support ofthe heart's weight. The cannulas may be physically embedded in the wallof the heart preservation chamber. Placing tension on the aorta servesto maintain aortic valve competency. However, the use of the inclinedsupport surface causes a reduction in the tension under which the aortais placed since much of the weight of the heart is supported by thesupport surface. Compared to a heart vertically suspended by the aorta,this results in less stress on the aorta which lessens the damage to theaorta itself, reduces the chance of the aorta detaching from the aortaconnector (cannula) during use, results in a shorter and more compactorgan chamber that reduces the weight and size of a preservation systemfor transport, and gives the heart mechanical support to keep it fromswinging and otherwise moving during transport. In addition, suspensionof the heart at 90 degrees (vertically) will interfere with the diameterof the coronary Ostia (the inlet of the coronary vessels) and thus mayinterfere with the blood volume perfusing the heart resulting in anischemic organ (lack of blood supply).

[0013] A problem with placing the heart in a horizontal position is thatthe resulting lack of tension on the aortic root will interfere with theleaflets' competency. This will result in aortic valve incompetence andwill decrease, if not eliminate, the coronary blood flow. This willresult in ischemia to the preserved organ and damage to the myocardialtissue. In addition to valve problems, placing the heart horizontally ona flat surface may place pressure on the surface coronary vessels (LeftAnterior Descending (LAD) or Posterior Descending (PDA) arteries) whichwill prevent blood supply to either the anterior or posterior heartsurfaces, respectively. A horizontal position also does not facilitatefluid drainage away from the heart.

[0014] The heart is preserved in two modes: a beating-non-working modeand a beating-working mode. In one embodiment of the procedure, theheart is perfused first in the beating-non-working state for 5-10minutes while all the cannulation takes place. Then, the heart isswitched to the beating-working mode. This allows the heart to then pumpblood in a physiologic fashion.

[0015] In the beating-non-working mode, a mechanical pump pumps blood tothe aorta (in an opposite direction to physiologic flow) to perfuse thecoronary vessels. The mechanical pump through the left atrial cannulawill trickle blood to the left atrium to supply oxygenated blood to fillthe left chambers. The right side of the heart still pumps the coronaryflow out towards the pulmonary artery and the fluid is collected througha cannula.

[0016] In the beating-working mode, a mechanical pump pumps the blood tothe left atrium to fill the heart. In this case, the heart muscle pumpsthe blood from the left ventricle to the aorta and the heart itselfpumps the coronary flow. The right side of the heart pumps the returnedcoronary flow to the pulmonary artery, where there is a cannula toreturn the blood to the fluid reservoir.

[0017] The inclined surface which supports the heart is in the shape ofa trough. This serves to (1) eliminate excessive tension on the aortictissue while maintaining enough tension to maintain aortic valvecompetency; (2) provide stability to the heart during transportation;and (3) provide for fluid drainage away from the heart. These functionscan also be performed by a V- or U-shaped groove. In the preferredembodiment, the heart rests on the inclined trough with the posteriorside facing up.

[0018] While this invention has been particularly shown and describedwith references to preferred embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the scope of the inventionencompassed by the appended claims.

What is claimed is:
 1. A heart preservation chamber comprising: ahousing that is at least partially transparent; an inclined troughsupporting the heart; and at least one inlet connector and at least oneoutlet connector delivering fluid to and removing fluid from the heart.2. A heart preservation chamber according to claim 1 wherein theinclined trough is inclined to an angle between about 10 degrees andabout 80 degrees.
 3. A heart preservation chamber according to claim 1wherein the inclined trough is inclined to an angle of about 30 degrees.4. A heart preservation chamber according to claim 1 wherein theinclined trough supports between 10% and 90% of the heart's weight.
 5. Aheart preservation chamber according to claim 1 wherein the connectorsconnect to the aorta, a pulmonary artery and a pulmonary vein.
 6. Aheart preservation chamber according to claim 5 wherein the connectorfor the aorta is located at an elevated end of the inclined trough.
 7. Aheart preservation chamber according to claim 5 wherein the connectorfor the pulmonary artery connects to an upper end of the chamber.
 8. Aheart preservation chamber according to claim 5 wherein the connectorfor the pulmonary vein connects to a lower end of the chamber.
 9. Aheart preservation chamber according to claim 1 further comprising acover which, when in a closed position, combines with the housing toprovide a sterile sealed enclosure.
 10. A heart preservation chamberaccording to claim 1 wherein the housing is made from a biocompatiblepolymer.
 11. A heart preservation chamber according to claim 1 whereinthe inlet and outlet connectors connect through a wall of the chamber toa perfusion circuit.